This invention relates to a method of processing a nozzle plate, a method of manufacturing a nozzle plate, a nozzle plate, an ink jet head, and image forming apparatus.
In an ink jet printer, the ink chamber of the ink jet head is filled with ink and it is jetted from a nozzle by the application of pressure to the ink chamber. After jetting, the ink meniscus, the surface of the ink, is withdrawn into the nozzle. After that, the ink chamber is refilled with ink from the ink tank, to be ready for the next jetting of ink.
However, because the pressure, which is applied for jetting ink, remains and fluctuates after the jetting of ink owing to the delay of the ink following the pressure applied, the ink meniscus vibrates. Owing to the remaining pressure fluctuation, sometimes the ink in the nozzle overflows the outlet for jetting to the outside. The ink, which has overflowed onto the surface of the nozzle plate, is next withdrawn into the nozzle by being brought into negative pressure, but the surface of the nozzle plate is smudged by the ink which has overflowed. If the ink droplet which is jetted next comes in contact with this smudge, the direction of jetting is deviated, or jetting is often made impossible; thus, the smudge of the nozzle plate makes one of big causes of the deterioration of image quality.
In order to prevent the smudge of the nozzle plate with ink, it has been put into practice that an ink-repellent processing is applied to the surface of the nozzle plate. If the surface of the nozzle plate is subjected to an ink-repellent processing, when ink meniscus comes outside the jetting outlet, it can be prevented that the ink overflows onto the surface of the nozzle plate, or spreads out by wetting the surface.
On top of the nozzle plate, if the inside of the nozzle hole is processed for repelling ink, the nozzle plate is made more scarcely to be smudged and jetting is stabilized. Because the ink meniscus is formed at the border of the portion subjected to the processing for repelling ink and the portion not subjected to the ink-repellent processing, if this border is located at a position retracting into the nozzle hole for a certain length, jetting is stabilized and the flying direction of the ink droplet is also stabilized. Further, even though the meniscus vibrates, the surface of the nozzle plate is hardly smudged, because ink is difficult to come out onto the surface of the nozzle plate.
If the entering length of the portion processed for repelling ink is too long, the resistance for jetting ink becomes large, to reduce the amount of ink jetting. Further, an air bubble is easy to be sucked into the ink chamber. On the contrary, if the entering length is too short, the surface of the nozzle plate is easy to be smudged, and the direction of the ink droplet is easy to deviate, to cause the jet-stabilizing effect to be lost. Because there are several tens to several hundreds of nozzle holes in one nozzle plate, it is especially important to apply the ink-repellent processing to the outlet portion of every nozzle hole for a constant length and uniformly. If the length of the processed portion varies from one nozzle to another nozzle, the amount of jetted ink droplet and the flying direction also vary from one to another, to reduce image quality to a large extent.
Further, on the other hand, at the ink inlet side in the nozzle hole, a film having familiarity for ink (hereinafter a coined word xe2x80x9cink-familiarxe2x80x9d will be used for the phrase xe2x80x9chaving familiarity for inkxe2x80x9d) is formed in order that ink may flow smoothly into the nozzle. It is desired that the portion of this ink-familiar film also enters into every nozzle uniformly, because it influences the amount of ink droplet to be jetted and the flying direction.
It is noted in the publications of the unexamined patent applications S48-37030 and S57-107848 etc. that the surface of the nozzle plate and the inside of the nozzle holes for a certain depth are coated with an ink-repellent material by sputtering after the nozzle holes have been formed in the nozzle plate. However, it is very difficult to apply by sputtering an ink-repellent processing to the portion near the outlet inside the nozzle holes for a constant length.
In the publication of the unexamined patent application S64-87359, it is noted that the nozzle holes are filled with a natural wax and the wax attached to the end surface of the holes is wiped off, then the surface of the nozzle plate and an ink-repellent film is formed at the portion near the jetting outlet of the nozzle holes by coating with tetrafluoroethylene using the plasma polymerization method, and after that, the wax is solved and removed.
In the publication of the unexamined patent application H10-157106, it is noted that an ink-familiar film is provided at the ink inlet side by electrodeposition coating with the ink outlet side of the nozzle plate protected by a protective sheet, then the protective sheet is removed and an ink-repellent film is provided at the ink outlet side of the nozzles by electrodeposition coating.
In the publication of the unexamined patent application H7-125220, it is noted that a resin film is laminated and inserted from the rear side of the nozzle plate made of a stainless steel, and the surface of the nozzle plate and the outlet portion of the nozzle holes are processed for repelling ink, to make the ink-repellent processing get into the inside of the nozzle holes for a certain length from the surface, without being limited to the surface.
In any one of the former examples, the ink-repellent processing is carried out after the formation of the holes. At that time, if the inside of the nozzle holes and the rear surface is subjected to the ink-repellent processing, air bubbles stagnate there, or the nozzle plate can not be bonded to the main body. For that reason, it has been put into practice that first the rear surface and the inside of the nozzle holes are masked, then an ink-repellent processing is carried out, and the masking material is removed. For example, as the representative method of masking, a method as described in the publication of the unexamined patent application S64-87359 such that the nozzle holes are filled with a resin material and the rear surface of the nozzle plate is covered with the resin material, and a method as described in the publication of the unexamined patent application H10-157106 such that the rear surface of the nozzle plate is laminated with a resin film can be cited; many are methods such that the resin material overflowing onto the front surface is removed and an ink-repellent processing is applied only to the front surface.
However, it is difficult to control the method in which the nozzle holes are filled with a resin material with a high precision to determine the entering length of the portion subjected to the ink-repellent processing, its cost comes to a high value, and mass production can not be expected. Further, it is difficult to remove the resin material from the nozzle holes completely after processing. Because the processing is troublesome, the fluctuation of the length among the nozzles is large, and the jet stabilization of ink droplets is sometimes made worse on the contrary.
Generally speaking, several tens to several hundreds of nozzles having a hole diameter of 20 to 60 xcexcm are formed in the nozzle plate, therefore, it is extremely difficult to fill each of the nozzles with a photosensitive resin material uniformly with a precision in the order of xcexcm. If the entering length of the ink-repellent film have a fluctuation among the nozzles, the amount of ink jetted from each of the nozzles varies from one nozzle to another, to make a cause to lower image quality by a great deal. Further, it is also difficult to remove completely the resin material which has been crosslinked after processing from the nozzle holes having a diameter of 20 to 60 xcexcm. If the crosslinked resin material is removed in a severe condition, sometimes the ink-repellent film coated by electrodeposition is peeled off too. These problems occur in the same way in the case where the ink-familiar film is made to get into the nozzle holes for a constant length.
This invention was made in view of the above-described points, and is a method in which it is controlled with a high precision by using a gas or a liquid the entering length of the film based on a processing liquid formed in the nozzle holes of the nozzle plate; owing to it, it is possible to improve the jet stabilization of ink droplets and image quality in a simple manner. Further, it is an object of the invention to provide a method of processing a nozzle plate, a method of manufacturing a nozzle plate, and a nozzle plate which make easy the control of the entering length, is of low cost, and is able to be applied to mass production.
In order to solve the above-described problems and accomplish the object, this invention has any one of the following structures.
(1) A method of processing a nozzle plate for forming a film (a film layer) based on a processing liquid on said nozzle plate comprising the steps of
bringing a processing liquid into contact with said nozzle plate having a plurality of nozzles (nozzle holes) for jetting ink from one side of said nozzle plate,
bringing a gas into contact with said nozzle plate from the other side, and
forming an interface (a boundary surface) by said processing liquid and said gas.
According to the invention set forth in the structure (1), a processing liquid is brought into contact with the nozzle plate from one side of it, and a gas is brought into contact with it from the other side, to form an interface by the processing liquid and the gas, then a film based on the processing liquid is formed on the nozzle plate; thus, by utilizing the interface between the processing liquid for forming the film and the gas, it becomes possible to control it freely and easily with a high precision, the entering length into the nozzle holes of the film formed on the nozzle plate, and further, by using a gas, the formation of the film and its control can be done with a structure which is simpler than before. In the above, the film means the film which is formed by the precipitation of the substance in the processing liquid.
(2) A method of processing a nozzle plate as set forth in the structure (1), wherein the entering length into the nozzle of the aforesaid film formed is controlled by controlling the position of the aforesaid interface.
According to the invention described in the structure (2), by controlling the position of the interface, the entering length of the film formed into the nozzle can be controlled easily with a simple structure.
(3) A method of processing a nozzle plate as set forth in the structure (1) or (2), wherein the aforesaid position of the interface is controlled by controlling the pressure of the aforesaid gas.
According to the invention described in the structure (3), it becomes possible to control it freely and easily with a higher precision, the entering length into the nozzle holes of the film formed on the nozzle plate by controlling the position of the interface by controlling the pressure of the gas, and it is possible to carry out the formation of the film and its control with a simpler structure.
(4) A method of processing a nozzle plate as set forth in any one of the structures (1) to (3), wherein the aforesaid processing liquid is brought into contact with the aforesaid nozzle plate after the aforesaid gas has been brought into contact with it.
According to the invention described in the structure (4), by bringing the processing liquid into contact with the nozzle plate after the gas is brought into contact with it, the film is easily formed by utilizing the interface between the processing liquid and the gas.
(5) A method of processing a nozzle plate for forming a film based on a processing liquid on said nozzle plate comprising the steps of
bringing a processing liquid into contact with said nozzle plate having a plurality of nozzles for jetting ink from one side of said nozzle plate,
bringing a liquid which is different from said processing liquid into contact with said nozzle plate from the other side, and
forming an interface by said processing liquid and said liquid.
According to the invention described in the structure (5), a processing liquid is brought into contact with the nozzle plate from one side of it, and a liquid which is different from the processing liquid is brought into contact with it from the other side, to form an interface by the processing liquid and the liquid, then a film based on the processing liquid is formed on the nozzle plate; thus, by utilizing the interface between the processing liquid for forming the film.and the liquid, it becomes possible to control it freely and easily with a high precision, the entering length into the nozzle holes of the film formed on the nozzle plate.
(6) A method of processing a nozzle plate as set forth in the structure (5), wherein the entering length into the nozzles of the aforesaid film formed is controlled by controlling the position of the aforesaid interface.
According to the invention described in the structure (6), by controlling the position of the interface, the entering length of the film formed into the nozzles can be controlled easily with a simple structure.
(7) A method of processing a nozzle plate as set forth in the structure (5) or (6), wherein the aforesaid position of the interface is controlled by controlling the pressure of the aforesaid liquid.
According to the invention described in the structure (7), it becomes possible to control it freely and easily with a higher precision, the entering length into the nozzle holes of the film formed on the nozzle plate by controlling the position of the interface by controlling the pressure of the liquid.
(8) A method of processing a nozzle plate as set forth in any one of the structures (5) to (7), wherein the aforesaid processing liquid is brought into contact with the aforesaid nozzle plate after the aforesaid liquid has been brought into contact with it.
According to the invention described in the structure (8), by bringing the processing liquid into contact with the nozzle plate after the liquid is brought into contact with it, the film is easily formed by utilizing the interface between the processing liquid and the liquid.
(9) A method of processing a nozzle plate as set forth in any one of the structures (1) to (8), wherein the aforesaid film formed is an ink-repellent film.
According to the invention described in the structure (9), because the film is an ink-repellent film, the nozzle plate is hardly smudged, and the jetting of ink droplets is stabilized. The ink-repellent film in this invention means a film having a contact angle of 90 degrees or over with the ink. For the material of this ink-repellent film, one including a fluorine-contained resin or a silicone resin is desirable.
(10) A method of processing a nozzle plate as set forth in the structure (9), wherein a processing for making the surface to be ink-familiar is carried out after the formation of the aforesaid ink-repellent film.
According to the invention described in the structure (10), by carrying out the processing for making the surface to be ink-familiar after the formation of the ink-repellent film, ink becomes easy to enter into the nozzle, to stabilize the jetting of ink droplets.
(11) A method of processing a nozzle plate as set forth in the structure (9), wherein a processing for making the surface to be ink-familiar is carried out before the formation of the aforesaid ink-repellent film.
According to the invention described in the structure (11), by carrying out the processing for making the surface to be ink-familiar before the formation of the ink-repellent film, it becomes unnecessary to form an ink-familiar film while ink is easy to enter into the nozzle to stabilize the jetting of ink droplets.
(12) A method of processing a nozzle plate as set forth in any one of the structures (1) to (8), wherein the aforesaid film formed is an ink-familiar film.
According to the invention described in the structure (12), the film formed is an ink-familiar film and ink becomes easy to enter into the nozzles to stabilize the jetting of ink droplets. The ink-familiar film in this invention means a film having a contact angle with the ink smaller than 90 degrees.
(13) A method of processing a nozzle plate as set forth in the structure (12), wherein an ink-repellent film is formed after the formation of the aforesaid ink-familiar film.
According to the invention described in the structure (13), by forming an ink-repellent film after the formation of the ink-familiar film, ink becomes easy to enter into the nozzle to stabilize the jetting of ink droplets, and the surface of the nozzle plate becomes difficult to be smudged.
(14) A method of processing a nozzle plate as set forth in any one of the structures (1) to (13), wherein the position of the aforesaid interface is controlled by tightly closing one side of said nozzle plate.
According to the invention described in the structure (14), because the position of the interface is controlled by tightly closing one side of the nozzle plate, the position of the interface is determined by the inner volume of the nozzle, and if the inner volume of the nozzle is kept constant, the pressure is made to be constant, to make it possible to keep constant the position of the interface for every nozzle.
(15) A method of processing a nozzle plate as set forth in the structure (14), wherein the position of the aforesaid interface is controlled by laminating a film on one side of said nozzle plate to tightly close it.
According to the invention described in the structure (15), because the position of the interface is controlled by laminating a film on one side of the nozzle plate to tightly close it, the position of the interface is determined by the inner volume of the nozzle, and if the inner volume of the nozzle is kept constant, the pressure is made to be constant, to make it possible to keep constant the position of the interface for every nozzle.
(16) A method of processing a nozzle plate as set forth in the structure (14) or (15), wherein the aforesaid tight closing is carried out from the side of ink inflow of the aforesaid nozzle plate.
According to the invention described in the structure (16), by carrying out the tight closing from the side of ink inflow of the nozzle plate, it is possible to form the film from the jetting side of ink droplets.
(17) A method of processing a nozzle plate as set forth in any one of the structures (1) to (16), wherein the aforesaid film is formed by electrodeposition.
According to the invention described in the structure (17), by electordeposition processing, a film of 1 to several xcexcm can be formed easily, uniformly, and firmly on a electrically conductive substrate.
(18) A method of processing a nozzle plate as set forth in any one of the structures (1) to (16), wherein the aforesaid film is formed by plating processing.
According to the invention described in the structure (18), the film can be formed easily, uniformly, and firmly by plating processing.
(19) A method of processing a nozzle plate as set forth in any one of the structures (1) to (18), wherein the aforesaid nozzle plate is made of a metal.
According to the invention described in the structure (19), because the nozzle plate is made of a metal, a filmed ink jet head can be simply and easily manufactured.
(20) A method of processing a nozzle plate as set forth in any one of the structures (1) to (18), wherein the aforesaid nozzle plate is made of a resin.
According to the invention described in the structure (20), because the nozzle plate is made of a resin, a filmed ink jet head can be simply and easily manufactured.
(21) A method of processing a nozzle plate as set forth in the structure (20), wherein the aforesaid nozzle plate has a metallic film on its surface.
According to the invention described in the structure (21), because the nozzle plate has a metallic film on its surface, filming can be easily done by using electrodeposition coating or electroplating.
(22) A method of processing a nozzle plate as set forth in the structure (9), wherein the entering length of the aforesaid ink-repellent film into the nozzle is from 5 xcexcm to 10 xcexcm.
According to the invention described in the structure (22), the entering length of the ink-repellent film into the nozzle is from 5 xcexcm to 10 xcexcm; therefore, by making it 5 xcexcm or over, the jet stabilizing effect becomes larger, and the fluctuation of the jetting direction of ink droplets is reduced. Further, by making it 10 xcexcm or under, it can be suppressed for the jetting resistance to become large, and the amount of droplet fired is more stabilized. Besides, when the meniscus vibrates, the overflow of the ink onto the surface of the nozzle plate and the sucking-in of bubbles into the ink chamber can be more reduced.
(23) A method of processing a nozzle plate as set forth in the structure (9), wherein the fluctuation of the entering length of the aforesaid ink-repellent film into the nozzle is 1.0 xcexcm or under.
According to the invention described in the structure (23), because the fluctuation of the entering length of the aforesaid ink-repellent film into the nozzles is 1.0 xcexcm or under, the amount of droplet fired is more stabilized. In this specification, the fluctuation of the entering length is expressed by the deviation, which is the difference between the entering length in each of the nozzles and the average of the values of the entering length over all the nozzles of the nozzle plate. Further, xe2x80x9cthe fluctuation of the entering length is 1.0 xcexcm or underxe2x80x9d means the state such that the deviation of the entering length in at least 95% of all the nozzles is 1.0 xcexcm or under.
(24) A method of manufacturing a nozzle plate comprising the steps of
boring a plurality of nozzles for jetting ink in a plate,
carrying out a processing for making ink-familiar the plate provided with said nozzles,
forming an interface by bringing an ink-repellent processing liquid into contact with said plate from its ink jetting side and bringing a gas into contact with said plate from its ink inflow side, and after that
forming an ink-repellent film on said plate.
According to the invention described in the structure (24), the jetting stability of ink droplets is improved, by boring a plurality of nozzles for jetting ink in a plate, carrying out a processing for making ink-familiar the plate provided with the nozzles, forming an interface by bringing an ink-repellent processing liquid into contact with said plate from its ink jetting side and bringing a gas into contact with said plate from its ink inflow side, and after that, forming an ink-repellent film on said plate.
(25) A method of manufacturing a nozzle plate comprising the steps of
boring a plurality of nozzles for jetting ink in a plate,
carrying out a processing for making ink-familiar the plate provided with said nozzles,
forming an interface by bringing an ink-repellent processing liquid into contact with said plate from its ink jetting side and bringing a liquid which is different from said processing liquid into contact with said plate from its ink inflow side, and after that
forming an ink-repellent film on said plate.
According to the invention described in the structure (25), the jetting stability of ink droplets is improved, by boring a plurality of nozzles for jetting ink in a plate, carrying out a processing for making ink-familiar the plate provided with the nozzles, forming an interface by bringing an ink-repellent processing liquid into contact with said plate from its ink jetting side and bringing a liquid which is different from said processing liquid into contact with said plate from its ink inflow side, and after that, forming an ink-repellent film on said plate.
(26) A method of manufacturing a nozzle plate as set forth in the structure (24) or (25), wherein the aforesaid boring of the nozzles is carried out by using a punch.
According to the invention described in the structure (26), the holes can be formed simply and with a high precision by using a punch.
(27) A nozzle plate having a plurality of nozzles for jetting ink, said nozzle plate being provided with
an ink-repellent film at the ink jetting side of said nozzle plate and in the nozzles,
the fluctuation of the entering length of said ink-repellent film into the nozzles being 1.0 xcexcm or under among the nozzles.
According to the invention described in the structure (27), the variation of the amount of droplet fired from one nozzle to another can be suppressed to improve the jetting stability of ink droplets by it, that the nozzle plate is provided with an ink-repellent film on its one side and in the nozzles, and the fluctuation of the entering length of the ink-repellent film into the nozzles is made 1.0 xcexcm or under among the nozzles. In this specification, the fluctuation of the entering length is expressed by the deviation, which is the difference between the entering length in each of the nozzles and the average of the values of the entering length over all the nozzles of the nozzle plate. Further, xe2x80x9cthe fluctuation of the entering length is 1.0 xcexcm or underxe2x80x9d means the state such that the deviation of the entering length in at least 95% of all the nozzles is 1.0 xcexcm or under.